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Preserving the Gingival Architecture in Hopeless Teeth

Clinical Considerations and Case Report

Ramón García-Adámez Soto, DDS, MS

Traditionally, one of the primary objectives of implant therapy was to ensure osseointegration and to deliver a restoration that would reconstruct the form and improve function. While these objectives remain a priority in contemporary restorative treatment, alternative concerns include the preservation of tissue and optimization of the soft tissue contour, simplification of treatment, reduction of sequences, patient comfort, and development of an optimal aesthetic result.1-4

When treating failing adjacent teeth in the aesthetic zone with an otherwise healthy periodontium and complete dentition in patients with a high smile line, the development of optimal gingival aesthetics is paramount. Bone resorption, unfortunately, is common following the removal of adjacent anterior teeth, and it is extremely difficult to avoid remodeling of gingival tissue levels and interproximal papillae.5 A combination of improper implant placement and/or inadequate osseous-gingival support may similarly result in compromised aesthetic outcomes. This article evaluates factors that may influence the dynamics of peri-implant gingival aesthetics in the event of adjacent anterior failing teeth; it also describes a surgical and prosthodontic technique that may assist the restorative team in achieving a predictable objective.

Case Presentation

Clinical and Radiographic Evaluation

A 30-year-old non-smoking female patient in general good health and with no contraindications to treatment presented with questionable maxillary left central and lateral incisors. The two teeth previously received endodontic treatment, cast post and cores, and metal-ceramic crowns (Figure 1). The patient, with a high smile line, preferred frequent uncementations of the two incisors. The radiographic evaluation revealed correct endodontic therapies and no signs of infection or periapical radiolucency (Figure 2). Removal of the prosthesis showed a severe decay of the remaining coronal structure and a poor ferrule effect of both teeth.

Treatment options were reviewed with the patient, including orthodontic extrusion and conservation of teeth with implant-retained ceramic crowns. Based on the patient’s desire for immediate aesthetics and reduced treatment time, combined with the patient’s excellent periodontal conditions, immediate implant placement with immediate provisionalization following tooth extraction was selected.

Surgical Procedure

Preoperative examination included the measurement of the distance between the crestal bone and the contact point as well as the distance between the free margin and the crestal bone on the labial, palatal, mesial, and distal aspects of the central incisor. The case was considered type I (buccal bone intact, thick biotype).4

A preliminary impression was made and diagnostic casts were obtained with type IV dental stone to fabricate a provisional crown that would be relined chairside on a provisional abutment. The anterior maxillary region was anesthetized, and the left central incisor was carefully lifted out of its socket with an extraction system that prevented damage to the soft tissues and surrounding bone, enlargement of the extraction socket, or the buccal plate fracture.

An internal-connection osseointegrated implant was placed to restore tooth #9(21) according to the manufacturer’s protocol and, with reference to three-dimensional positioning, approximately 3 mm apical to the free gingival margin and leaving a space of 2 mm with the buccal plate. The implant showed adequate initial stability at 35 Ncm (Figure 3).

Following implant placement, a temporary abutment was screwed in and a shell provisional restoration was relined intraorally. When the resin was cured, a concave individual emergence profile was created extraorally, cured in the laboratory, and prepared with diamond burs to its ideal form. Because the screw access hole of the abutment was on the vestibular side, it was decided to connect the acrylic screw-retained crown and to fabricate a composite laminate over it (Figure 4). Appropriate antibiotics and analgesics were prescribed for postoperative use, and the patient was advised against adverse functioning on the implant restoration during the five-month healing phase.

Preparation of the Definitive Gingival Architecture

In this case, the gingival levels of the central incisors were more coronal than the levels of the lateral incisors, which accounted for some of the gingival recession experienced. The provisional crown was unscrewed and removed (Figure 5) and a pick-up implant impression was made using a polyether impression material (Figures 6 and 7).

A master cast was fabricated from the impression and a wax-up was made with the final gingival architecture of the incisor. At this stage, and with the help of a silicone index, the cast was trimmed around the implant to create an emergence profile that matched the contour of the tooth in the diagnostic wax-up, and a 1-mm submerged ovate pontic was created in the place of lateral incisor #10(22) (Figure 8).

The cast was isolated with petroleum jelly and a provisional restoration was fabricated (Figure 9). After final adjustments, recontouring, and polishing, lateral incisor #10(22) was horizontally sectioned and an ovate anatomy similar to the ovate pontic was created 3 mm subgingivally before screwing in the second provisional restoration (Figure 10).A follow-up visit one week later revealed minimal gingival changes and the individual emergence profile was modified, applying flowable composite to the acrylic restorations until an optimal tridimensional gingival architecture was achieved (Figures 11 and 12).

Final Restoration

A customized zirconia abutment and a two-piece zirconia bridge were selected. In order to maintain the gingival emergences and the soft tissue architecture, a final impression was made with the provisional restoration as a custom impression coping. A single-impression double-mix technique was applied with a fluid polyvinysiloxane material injected around the natural teeth, provisional screwed restoration, and the heavy-body material in the impression tray. The provisional restoration was unscrewed, and a laboratory implant analogue was connected, embedded, and locked into the impression material (Figure 12).

The final model was poured and the provisional restoration was replaced immediately after the stone was set. The definitive restoration was delivered two weeks later (Figure 13). The finished zirconia abutment was torqued to 35 Ncm and the definitive bridge was cemented (Figure 14).

Optimal soft tissue health, color, and texture were obtained (Figure 15). Two weeks later, the final aspect of the restorations revealed an excellent light transmission and an optimal aesthetic outcome at the gingival-prosthesis interface (Figures 16 and 17). The postoperative radiograph revealed development of a correct osseous architecture (Figure 18).

Discussion

In the natural dentition, tooth contour and bone architecture determine the gingival tissue height and form. Single-tooth implant sites with adjacent natural teeth (ie, full papilla, scallop-shaped bone, and soft tissue) can be restored and maintained with an ideal aesthetic outcome as the periodontium of the natural teeth support the bone level superior to the implant-abutment interface.6,7 Aesthetic implant treatment is, however, more difficult in multiple-tooth defects, because an ideal soft tissue frame with intact interdental papillae is difficult to create without an adjacent intact natural tooth attachment apparatus. Restorations of adjacent implants generally result in an interimplant papilla more apical than the interdental papillae of the adjacent dentition.5,8 According to the literature, only an average 3.4 mm of soft tissue height can be expected to form over the interimplant crest of bone.9It has been demonstrated also that a distance of at least 3 mm is necessary between two standard design implants in order to maintain the interproximal bone position after remodeling of the biologic width.10

Some authors have experienced that even with 3 mm of space between implants, the interproximal bone flattens, and is accompanied with the loss of a natural papilla form.11 Currently, some techniques have been described in an attempt to control alveolar resorption and preserve crestal bone height with adjacent implants: scalloped implants,12 the control of healing provisional abutments,13 platform switching,14,15 sequenced implant placement,16 or the placement of prefabricated zirconia abutments at the time of surgery.17,18

In the case presented herein, the root submergence technique (RST) was used to preserve the surrounding tissues and interdental bone height.19 The advantages of this technique include: a high level of predictability; a predictable recovery in adjacent implants postoperatively due to the decreased blood supply to the peri-implant soft tissue; resorption avoidance of the buccal plate; less risk; and reduced expense.

Conclusion

To obtain ideal implant aesthetics, the role of the interdental papilla is essential. The papilla height and form should be restored to the original situation observed in natural teeth in cases of adjacent failing teeth. In the case presented herein, various techniques were used to establish the ideal situation. This included atraumatic extraction procedures, immediate implant insertion, concave profile of the provisional abutment, and the root submergence technique. However, the most important factor in these cases is the management of the soft peri-implant architecture during the procedure in order to avoid soft tissue remodeling and resorption.